The present invention relates to the construction of a rotary actuator also known as a sector motor, in which a rotary element is swingable between a pair of spaced positions, and in particular, to such devices in which the rotary element is latched or held in a selected position after power has been removed therefrom.
Generally, the rotary actuator includes a magnetic armature element surrounded by one or more electromagnetic stator elements each having one or more windings which when driven provide a force field to drive the armature. Reference can be made to such devices as shown in the U.S. Pat. Nos. 3,694,782; 4,227,164; as well as 3,761,851; and 4,500,861. In order to overcome inherent slow speed, the prior art devices have resorted to the use of a large power input to operate the electromagnets and rather large masses of magnetic material to increase magnetic force. Multi-armed armatures with each arm having a winding are used to increase magnetic permeance, as are multi-electromagnets, each operated simultaneously to produce an increased flux pattern. As a result, the prior art devices have been expensive, complex, and generally quite large for the purposes intended.
A manifest need, therefore, exists for small, lightweight, and extremely fast-acting, low-voltage and long-lived motor devices for use in such installations as waveguides and other electro-mechanical systems. It is the object of the present invention to provide such device.
It is another object of the present invention to provide a rotary actuator which is maintained or latched in a given fixed position with or without power being supplied to the electromagnets.
It is an object of the present invention to provide a springless rotary actuator having a fail safe or return latching position, to which the armature automatically returns when electrical drive power is removed.
It is a further object of the present invention to provide an actuator wherein the range of angular movement is sufficiently large to provide for a mechanical advantage and a mechanical movement capable of operating mechanical switches or the like.
It is another object of the present invention to provide an actuator in which chattering, bouncing, and vibration are completely avoided.
These other objects and attendant advantages of the present invention, as well as numerous others, are set forth in the following disclosure.